Can I specify which version of Blender to run when rendering from a command line prompt (Linux)?
Blender doesn't need to be installed, so even if you have one version installed on your system, you can have other versions that sit in your filesystem and can be run without further operations. Apart from convenient launcher icons and multi-user availability, there is no advantage in "installing" Blender.

To get Blender 2.81a: on the compute machine:

# go to your home directory (or a convenient other place)
cd ~

# make a directory to store blender distributions, and enter it
mkdir blender-versions
cd blender-versions

# get the latest version of blender and extract the archive
wget https://download.blender.org/release/Blender2.81/blender-2.81a-linux-glibc217-x86_64.tar.bz2
tar -xvjf blender-2.81a-linux-glibc217-x86_64.tar.bz2


Now, from any directory, instead of just blender you can run:

~/blender-versions/blender-2.81a-linux-glibc217-x86_64/blender -b &lt;YOURFILE&gt; &lt;OPTIONS&gt;


If that seems too long, you can create an alias. Assuming your Linux machine uses bash, edit the file ~/.bashrc and add the line:

alias blender281='~/blender-versions/blender-2.81a-linux-glibc217-x86_64/blender'


After you restart your terminal, you'll be able to just use

blender281 -b &lt;YOURFILE&gt; &lt;OPTIONS&gt;


to run Blender 2.81a.

You can repeat the same operations with other distributions. Find a list of download links here: https://download.blender.org/release/